This invention relates to vapor degreasers and in particular, to modifications for conventional degreasers to reduce air pollution possibilities and meet air pollution control requirements.
A conventional vapor degreaser utilizes a rectangular tank with a quantity of liquid solvent in the lower portion, which solvent is heated to produce vapor, typically by passing steam through coils in the lower portion of the tank. A vapor condenser is incorporated in the tank, typically in the form of a plurality of cooling coils around the interior of the tank. Vapor rising from the liquid level to the cooling coils is condensed at the coils, collected in condensate troughs or the like, and after separation of water, the solvent is returned to the bottom of the tank. The vapor level is defined by the condensing coils with most of the vapor in the tank being in the zone between the liquid level and the vapor level.
In use, the part to be cleaned is positioned in the tank in the vapor zone between the liquid and vapor levels. The part may also be sprayed with liquid solvent if desired. Typical vapor degreasers and their use are shown in the Vapor Degreasing Handbook published by Electro Chemicals Division, Diamond Shamrock Corporation, publication EC-S-51a.
While most of the vapor is condensed at the vapor level, some of the vapor escapes upward through the open top of the tank. Various steps are being taken to reduce the amount of vapor which does escape, since this contributes to undesirable air pollution. The freeboard ratio is defined as the ratio of the depth of the tank between the open top and the vapor level to the width at the open top, and this freeboard ratio is one of the parameters which must be maintained within certain limits in order for a vapor degreaser to meet some present day air pollution control requirements.
By way of example, a typical vapor degreaser tank may have an inside depth of 161/2 inches and an inside width of 27 inches providing a freeboard ratio of 61%. However, some air pollution control requirements state that the freeboard ratio must be 75% or greater and many vapor degreasers of current design do not meet this requirement.
Therefore it is an object of the present invention to provide a modification for a vapor degreaser for increasng the freeboard ratio without otherwise affecting the construction and/or operation of the unit. A further object is to provide such a modification which is easily and inexpensively carried out with existing units and which can be accomplished in the field with a minimum of interruption to use in production.
Other objects, advantages, features and results will more fully appear in the course of the following description.